JP4374804B2 - Circuit breaker breaking mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a circuit breaker breaker mechanism such as a circuit breaker for wiring or an earth leakage breaker, and in particular, includes a latch that locks a toggle link in a closed state of a movable contact and a latch receiver that locks the latch. The present invention relates to the configuration of the engagement surface.
[0002]
[Prior art]
The circuit breaker breaking mechanism generally includes a pivotally supported latch, and a latch support that is pivotally supported and normally locks the latch to prevent its rotation. When the movable contact is closed, the toggle link is locked to maintain the shut-off spring in the stored state, and when the tripping device operates and the latch receiver is driven to rotate in the event of an abnormality, the latch is released. And the movable contact is opened by the stored force of the shut-off spring by unlocking the toggle link.
[0003]
FIG. 2 is a side view showing an example of this type of blocking mechanism, and FIG. 3 is a sectional view taken along line III-III in FIG. In FIG. 3, each phase circuit of the circuit breaker includes a current interrupting unit including a pair of front and rear fixed contacts 1 and 2 and a movable contact 3 bridging between them. The movable contact 3 is held by a movable contact holder 4 integrated with each pole made of an insulator, and is pressed against the fixed contacts 1 and 2 by a contact spring 5 made of a compression coil spring inserted between a case (not shown). ing. The movable contact 3 is pushed down as shown by a two-dot chain line by a shut-off lever 7 that receives a stored force of a shut-off spring 6 made of a torsion spring and is rotated clockwise in FIG. , 2 to cut off the current, but in the closed state shown in the figure, the cutoff lever 7 is constrained to the position shown by the solid line in the figure, and the cutoff spring 6 is maintained in the stored state.
[0004]
2 and 3, the illustrated shut-off mechanism is unitized with the mechanical parts supported by a frame 8 having side plates 8 a (FIG. 3) on the left and right sides (in FIG. 2, the front side plate 8 a is excluded). ing.). A butterfly-shaped operation handle 9 is rotatably supported on the frame 8 via a handle shaft 10, and a latch 11 is rotatably connected to the handle shaft 10. The latch 11 has a bifurcated shape having side plates on the left and right except for the L bent portion 11a at the tip, and sandwiches the operation handle 9 from both sides. On the other hand, the upper end of the upper link 12 is connected to the operation handle 9 via a connecting shaft 13, and the upper end of the lower link 14 is connected to the lower end of the upper link 12 via one end of a U-shaped pin 15. Each of the upper link 12 and the lower link 14 has side plates on the left and right, the upper link 12 sandwiches the operation handle from both sides, and the lower link 14 sandwiches the upper link 12 from both sides. The other end of the U-shaped pin 15 is hung on the latch 11 and restrains the upper link 12 and the lower link 14 with respect to the latch 11. The upper link 12 and the lower link 14 constitute a toggle link.
[0005]
A transmission pin 16 is attached to the lower end of the lower link 14, and both ends of the transmission pin 16 are slidably inserted and guided into an elongated hole 17 formed in the frame side plate 8a. Then, the other transmission pin 18 is attached to the blocking lever 7 so as to cross the transmission pin 16. That is, there is a pair of blocking levers 7, which are coupled to an opening / closing shaft 19 whose both ends are rotatably supported by a case (not shown) via a gap, and a transmission pin 18 extends between the blocking levers 7 and 7. It is installed. A pair of shut-off springs 6 and 6 are fitted into the opening / closing shaft 19 from both ends, one end of which is engaged with the transmission pin 18 and the other end is engaged with the frame 8. Therefore, the shut-off spring 6 is twisted and is in a stored state, and the push-out lever 6 is pushed from the transmission pin 18 to the transmission pin 16 as shown in FIG. A lifting force P is applied.
[0006]
The transmission pin 16 of the lower link 14 tries to move upward along the elongated hole 17 by the force P. As a result, the lower link 14 tries to rotate counterclockwise in FIG. 2 with the transmission pin 16 as a fulcrum. The upper end is restrained by the U-shaped pin 15, so that it cannot move and maintains the illustrated posture. At the same time, a tensile force Q acts on the latch 11 from the lower link 14 via the U-shaped pin 15. Therefore, the latch 11 tries to rotate clockwise in FIG. 2 with the handle shaft 10 as a fulcrum, but is latched by the latch receiver 20 and held in the illustrated posture. The latch receiver 20 is formed by bending a pair of left and right arms 20a in the middle of a vertically extending plate body, and having a rectangular window hole in the plate body portion in the vicinity of the arms 20a. Is supported by the frame 8 via a support shaft 21 that is pivotable, and the engagement surface 20b at the lower edge of the window hole engages with the engagement surface 11b of the latch 11 so that the latch 11 is not rotated. is doing. The latch receiver 20 receives force from the latch 11 and tries to rotate in the clockwise direction in FIG. 2, but the tongue piece 20c protruding left and right contacts the notch edge of the frame side plate 8a and is prevented from rotating. , Is held in the upright posture shown in the figure. A return spring 22 made of a compression coil spring is inserted between the lower end portion of the latch receiver 20 and the frame 8, and the latch receiver 20 is urged clockwise in FIG.
[0007]
In the above breaking mechanism, when the current flowing through the circuit breaker is in an overcurrent state, the latch receiver 20 receives a tripping operation force R as shown in FIG. Rotate in the direction. As a result, the latch 11 is unlocked and can be rotated clockwise. As a result, the toggle links 12, 14 collapse into a square shape, and the blocking lever 7 is driven to rotate clockwise in FIG. 3 by the stored force of the blocking spring 6. This interruption lever 7 pushes down the movable contact 3 via the movable contact holder 4 and separates it from the fixed contacts 1 and 2 to interrupt the current.
[0008]
FIG. 4 is an enlarged longitudinal sectional view showing a conventional engagement portion between the latch 11 and the latch receiver 20 in such a blocking mechanism. In FIG. 4, the latch 11 has its engaging surface 11b engaged with the engaging surface 20b of the latch receiver 20, but the engaging surfaces 11b and 20b are both flat surfaces, and they contact at, for example, point S. If this is the case, the engagement force T acts on the latch receiver 20 from the latch 11 based on the force Q (FIG. 2) acting on the latch 11 at the point S.
[0009]
When the overcurrent is generated, the tripping operation load for driving the latch receiver 20 to rotate counterclockwise is a sliding friction load when the engagement surface 11b is slid down from the engagement surface 20b. And the rotational moment M (FIG. 4) generated in the clockwise direction by the friction load acting between the support shaft 21 and the drag force of the return spring 22 and the engagement force T acting on the engagement surface 20b. The rotational moment M is M = rT, where r is the length of the arm from the axis of the support shaft 21 to the line of action of the engagement force T.
[0010]
[Problems to be solved by the invention]
In such a conventional shut-off mechanism, the engagement point between the latch 11 and the latch receiver 20 changes, for example, from S to S ′ in FIG. 4 depending on the component accuracy and assembly accuracy of the mechanism components, and the arm length corresponding to the change is also Δr. Is changed to (r + Δr) T. That is, the change in the position of the engagement point S directly affects the rotational load M. Therefore, conventionally, there has been a problem that the operating load of the latch receiver 20 is easily affected by the component accuracy and assembly accuracy of the shut-off mechanism, and therefore the tripping operation characteristics are likely to vary. Strictly speaking, when the position of the engagement point S changes, the engagement force T also changes. However, the arm length m (FIG. 2) from the handle shaft 10 supporting the latch 11 to the line of action of the engagement force T is related. Since it is sufficiently larger than the change in the position of the meeting point S, the change in the engagement force T itself can be ignored.
[0011]
On the other hand, as the rated current increases, the spring constant of the cutoff spring 6 increases, and the engagement force T increases accordingly. Therefore, when the same latch 11 and latch receiver 20 are used in a large model, the wear of the engaging surfaces 11b and 20b increases due to a large frictional force, and the secular change in the tripping operation characteristics increases.
The present invention has been made in view of the above-described problems, and its problem is to suppress changes in the engagement point between the latch and the latch receiver and wear of the engagement surface, and to obtain stable operating characteristics over a long period of time. It is in.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention includes a latch that is rotatably supported, and a latch receiver that is rotatably supported and normally locks the latch to prevent the rotation. The latch locks the toggle link in the closed state of the movable contact to maintain the shut-off spring in the energized state, and when the tripping device operates and the latch receiver is driven to rotate in an abnormal state, the latch is locked. The latch is engaged with the latch receiver in a circuit breaker circuit breaker mechanism that is removed and rotated, unlocking the toggle link and releasing the movable contact by the stored spring's stored force. The engagement arc surface of the latch receiver engaging with the convex arc surface is a concave arc surface having a radius of curvature larger than that of the convex arc surface, and the center of curvature of the concave arc surface is latched. Rotating support shaft of the receiver It is characterized in that to match the axis (claim 1).
According to such means, the line of action of the force T acting on the latch receiver from the latch always passes through the center of curvature of the concave arc surface regardless of the position of the engagement point S, and the center of curvature of the concave arc surface is latched. Since it is aligned with the axis of the pivot support shaft of the receiver, the change in the arm length r (FIG. 4) due to the change in the position of the engagement point S is minimized, and the line of action of the force T is Since the arm length r becomes 0 because the axis of the dynamic support shaft passes, the change in the arm length r due to the change in the position of the engagement point S also becomes 0.
[0013]
The engagement surface of the latch and the latch receiver according to claim 1 has a surface treatment layer composed of a low friction layer on the surface layer and a hardened layer therebelow, so that even in a large model, wear of the engagement surface is small and long Stable operating characteristics are maintained (claim 2).
The low friction layer is preferably composed of a nickel plating layer, and the hardened layer is preferably composed of a carburized layer .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention and is a longitudinal sectional view of an engaging portion between a latch and a latch receiver. In FIG. 1, the difference from the conventional configuration is that the engagement surface 11b of the latch 11 with the latch receiver 20 is formed in a convex arc surface, and the engagement surface 20b of the latch receiver 20 engaging with the convex arc surface 11b is This is a point formed on a concave arc surface having a larger radius of curvature than the convex arc surface 11b. Moreover, in FIG. 1, the center of curvature X of the concave arc surface 20 b coincides with the axis Y of the rotation support shaft 21 of the latch receiver 20 (Y = X). Therefore, in FIG. 1, the line of action of the engagement force T passes through the axis Y of the support shaft (r = 0) as shown in the figure, and no rotational load M is generated on the latch receiver 20 based on the engagement force T. Therefore, even if the locking point S changes to S ′, the rotational load M is always zero.
[0015]
On the other hand, in FIG. 1, the surface treatment layer which consists of the low friction layer (alpha) of the surface layer and the hardened layer (beta) of the lower layer is formed in the engaging surface 20b of the latch receptacle 20. As shown in FIG. Here, the base material γ of the latch receiver 20 is, for example, a cold rolled steel plate (SPCC), and the engagement surface 20b is first formed with a hardened layer β by carburizing and quenching, and then the surface thereof is plated with nickel. Thus, the low friction layer α is formed. The low friction layer α reduces friction when the engagement surface 11b slides down from the engagement surface 20b, reduces the tripping operation load, and extends the wear life of the engagement surface 20b. Further, the hardened layer β prevents the engagement surface 20b from being deformed by the engagement force T. That is, such surface treatment layers α, β reduce the friction of the engaging surface 20b and improve the strength. Even when the latch receiver 20 is shared by a large model, it has a low load and long life trip characteristic. Can be obtained. The surface treatment layers α and β can also be formed on the engagement surface 11 b of the latch 11.
[0016]
【The invention's effect】
As described above, according to the present invention, even if the position of the engagement point between the latch and the latch receiver varies depending on the component accuracy and assembly accuracy, the magnitude of the rotational load based on the engagement force acting on the latch receiver from the latch is almost affected. In addition, wear and deformation of the engagement surface are suppressed even in a large model, and stable tripping characteristics can be maintained for a long time.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an essential part of a blocking mechanism showing an embodiment of the present invention.
FIG. 2 is a side view showing a conventional blocking mechanism.
3 is a cross-sectional view taken along line III-III in FIG.
4 is a longitudinal sectional view of a main part of FIG.
[Explanation of symbols]
11 Latch 11b Engagement surface 20 Latch receiver 20b Engagement surface 21 Support shaft

Claims (3)

A latch supported in a rotatable manner; and a latch receiver that is supported in a pivotable manner and normally locks the latch to prevent the turning, and the latch is a toggle link in a closed state of the movable contact. The lock spring is locked to maintain the shut-off spring in the energized state, and when the tripping device operates in the event of an abnormality and the latch receiver is driven to rotate, the latch is released and rotated, and the chain of the toggle link is In the circuit breaker breaking mechanism that unlocks the movable contact by the stored force of the breaking spring by unlocking,
The engagement surface of the latch with the latch receiver is a convex arc surface, and the engagement surface of the latch receiver that engages with the convex arc surface is a concave arc surface having a larger radius of curvature than the convex arc surface, A circuit breaker breaking mechanism characterized in that the center of curvature of the concave arc surface coincides with the axis of the pivot support shaft of the latch receiver . 2. The circuit according to claim 1, wherein a surface treatment layer comprising a low friction layer as a surface layer and a hardened layer therebelow is formed on both or any one of the engagement surfaces of the latch and the latch receiver. Breaker breaking mechanism. 3. The circuit breaker breaking mechanism according to claim 2, wherein the low friction layer comprises a nickel plating layer, and the hardened layer comprises a carburized layer .

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